Kharijites in the context of "Takfir"

Islamic schools and branches have different understandings of Islam. There are many different sects or denominations, schools of Islamic jurisprudence, and schools of Islamic theology, or ʿaqīdah (creed). Within Sunnī Islam, there may be differences, such as different orders (tariqa) within Sufism, different schools of theology (Atharī, Ashʿarī, Māturīdī) and jurisprudence (Ḥanafī, Mālikī, Shāfiʿī, Ḥanbalī). Groups in Islam may be numerous (Sunnīs make up 87-90% of all Muslims), or relatively small in size (Ibadis, Ismāʿīlīs, Zaydīs).

Differences between the groups may not be well known to Muslims outside of scholarly circles, or may have induced enough passion to have resulted in political and religious violence (Barelvism, Deobandism, Salafism, Wahhabism). There are informal movements driven by ideas (such as Islamic modernism and Islamism), as well as organized groups with governing bodies (such as Nation of Islam). Some of the Islamic sects and groups regard certain others as deviant or not being truly Muslim (for example, Sunnīs frequently discriminate against Ahmadiyya, Alawites, Quranists, and sometimes Shīʿas). Some Islamic sects and groups date back to the early history of Islam between the 7th and 9th centuries CE (Kharijites, Mu'tazila, Sunnīs, Shīʿas), whereas others have arisen much more recently (Islamic neo-traditionalism, liberalism and progressivism, Islamic modernism, Salafism and Wahhabism), or even in the 20th century (Nation of Islam). Still others were influential historically, but are no longer in existence (non-Ibadi Kharijites and Murji'ah).

Schools of Islamic theology are various Islamic schools and branches in different schools of thought regarding creed. The main schools of Islamic theology include the extant Mu'tazili, Ash'ari, Maturidi, and Athari schools; the extinct ones include the Qadari, Jahmi, Murji', and Batini schools.

The main schism between Sunni, Shia, and Khariji branches of Islam was initially more political than theological, but theological differences have developed over time throughout the history of Islam.

The First Fitna (Arabic: الفتنة الكبرى) was the first civil war in the Islamic community. It led to the end of the Rashidun Caliphate and the establishment of the Umayyad Caliphate. The civil war involved three main factions; the supporters of the fourth Rashidun caliph Ali, the supporters of Uthman, primarily led by Mu'awiya and Aisha, and the Kharijites.

The roots of the first civil war can be traced back to the assassination of the second caliph, Umar. Before he died from his wounds, Umar formed a six-member council which elected Uthman as the next caliph. During the final years of Uthman's caliphate, he was accused of nepotism and killed by rebels in 656. After Uthman's assassination, Ali was elected the fourth caliph. Aisha, Talha, and Zubayr opposed Ali's accession and revolted against Ali to depose him. The two parties fought the Battle of the Camel in December 656, from which Ali emerged victorious. Afterwards, Mu'awiya, the long-time governor of the Levant, refused to recognise Ali as caliph and declared war. The two parties fought the Battle of Siffin in July 657, which ended in a stalemate and arbitration.

The Second Fitna was the second civil war in the Islamic community during the early Umayyad Caliphate. It followed the death of the first Umayyad caliph Mu'awiya I in 680, and lasted for about twelve years. The war involved the defeat of three main challenges to the authority of the Umayyad dynasty, the first by Husayn ibn Ali, as well as his supporters including Sulayman ibn Surad and Mukhtar al-Thaqafi who rallied to avenge his death in Iraq, the second by Abd Allah ibn al-Zubayr who proclaimed himself caliph in Mecca and Medina and would be nominally recognized throughout most of the Caliphate, and the Kharijites who took over central Arabia and southern Iraq and Persia.

The roots of the civil war go back to the First Fitna. After the assassination of the third Rashidun caliph Uthman, the Islamic community experienced its first civil war over the immediate question of retribution for his murder. Following the assassination of the fourth Rashidun caliph Ali in 661 and the abdication of his successor Hasan the same year, Mu'awiya became the sole ruler of the caliphate. Mu'awiya's unprecedented decision to nominate his son Yazid as his heir sparked opposition, and tensions soared after Mu'awiya's death. Husayn ibn Ali was invited by the pro-Alids of Kufa to overthrow the Umayyads but was killed with his small company en route to Kufa at the Battle of Karbala in October 680. Yazid's army suppressed anti-government rebels in Medina in August 683 and subsequently besieged Mecca, where Ibn al-Zubayr had established himself in opposition to Yazid. After Yazid died in November the siege was abandoned, and Umayyad authority would soon collapse throughout the caliphate following the death of his son except in parts of Syria where Marwan I was proclaimed caliph; most provinces recognized Ibn al-Zubayr as caliph. A series of pro-Alid movements demanding to avenge Husayn's death emerged in Kufa, beginning with Ibn Surad's Penitents movement, which was crushed by the Umayyads at the Battle of Ayn al-Warda in January 685. Kufa was then taken over by Mukhtar, who rallied Husayn's supporters and the disenfranchised mawali to his cause. Though his forces routed a large Umayyad army at the Battle of Khazir in August 686, Mukhtar and his supporters were slain by the Zubayrids in April 687 following a series of battles. Under the leadership of Marwan, the Umayyads would consolidate their power over Syria and retake Egypt from the Zubayrids, and under his successor Abd al-Malik ibn Marwan, the Umayyads would reconquer Iraq after defeating the Zubayrids at the Battle of Maskin in 691 and would reassert their control over the Caliphate after killing Ibn al-Zubayr in the second siege of Mecca in 692, while their general Al-Hajjaj ibn Yusuf would suppress the Kharijites in the years afterwards.

Ahkam (Arabic: أحكام, romanized: aḥkām, lit. 'rulings', plural of ḥukm, حُكْم) is an Islamic term with several meanings. In the Quran, the word hukm is variously used to mean arbitration, judgement, authority, or God's will. In the early Islamic period, the Kharijites gave it political connotations by declaring that they accept only the hukm of God (حُكْمُ اللّهِ). The word acquired new meanings in the course of Islamic history, being used to refer to worldly executive power or to a court decision.

Ahkam commonly refers to specific Quranic rules, or to the legal rulings/judgements/decisions derived using the methodology of fiqh. Sharia rulings fall into one of five categories known as "the five decisions" (al-aḥkām al-khamsa): mandatory (farḍ or wājib), recommended (mandūb or mustaḥabb), neutral/permissible (mubāḥ), disliked (makrūh), and forbidden (ḥarām).

Ibadism (Arabic: الإباضية, romanized: al-ʾIbāḍiyya, Arabic pronunciation: [alʔibaːˈdˤijja]) is a branch of Islam whose roots go back to the Kharijite secession from the fourth Caliph, Ali ibn Abi Talib. It is a moderate subsect that has persisted and led to the creation of Ibadi communities in various areas in the Middle East and Africa.

The followers of the Ibadi sect are known as the Ibadis or, as they call themselves, The People of Truth and Integrity (Arabic: أهل الحقّ والاستقامة). Contemporary Ibadis may object to being classified as Kharijites. They are much less numerous than the two largest Muslim denominations: Sunnis—who account for 85–90 percent of the Muslim world—and Shias.

Wahhabism is a Salafi revivalist movement within Sunni Islam named after the 18th-century Hanbali scholar Muhammad ibn Abd al-Wahhab. It was initially established in the central Arabian region of Najd and later spread to other parts of the Arabian Peninsula, and was the official policy of Saudi Arabia until 2022. Despite being founded on the principles of Sunni Islam, the Hanbalite scholars Ibn Taimiyya and Ibn al-Qayyim in particular, Wahhabism may also refer to doctrinal differences distinct from other forms of Sunni Islam. Non-Wahhabi Sunnis also have compared Wahhabism to the belief of the Kharijites and loyalist monarchism despite the two belief systems being contradictory to each other.

The Wahhabi movement staunchly denounced rituals related to the veneration of Muslim saints and pilgrimages to their tombs and shrines, which were widespread amongst the people of Najd. Ibn 'Abd al-Wahhab and his followers were highly inspired by the Hanbali scholar Ibn Taymiyya (1263–1328 CE/AH 661–728) who advocated a return to the purity of the first three generations (salaf) to rid Muslims of bid'a (innovation) and regarded his works as core scholarly references in theology. While being influenced by Hanbali school, the movement repudiated taqlid to legal authorities, including oft-cited scholars such as Ibn Taymiyya and Ibn Qayyim (d. 1350 CE/AH 751).